Simplify the following expression: $ x = \dfrac{r + 4}{-9} + \dfrac{3}{4} $
In order to add expressions, they must have a common denominator. Multiply the first expression by $\dfrac{4}{4}$ $ \dfrac{r + 4}{-9} \times \dfrac{4}{4} = \dfrac{4r + 16}{-36} $ Multiply the second expression by $\dfrac{-9}{-9}$ $ \dfrac{3}{4} \times \dfrac{-9}{-9} = \dfrac{-27}{-36} $ Therefore $ x = \dfrac{4r + 16}{-36} + \dfrac{-27}{-36} $ Now the expressions have the same denominator we can simply add the numerators: $x = \dfrac{4r + 16 - 27}{-36} $ $x = \dfrac{4r - 11}{-36}$ Simplify the expression by dividing the numerator and denominator by -1: $x = \dfrac{-4r + 11}{36}$